Kerberos is an authentication and security mechanism that may allow devices and individuals communicating over a non-secure network to prove their identity to one another in a secure manner. Kerberos and other such authentication systems may protect against eavesdropping and replay attacks on the communication system. An eavesdropping attack may be where an intruder may monitor a communication to obtain data in the communication. A replay attack may be where an intruder monitors an authentication session, such as when a password or other credential is transmitted, and the intruder may replicate the credential posing as the original sender to gain access to the authentication service.
Kerberos is only one of many different types of authentication and security mechanisms. Kerberos is based on a Needham-Schroeder protocol and is an example of a system that may use a symmetric encryption algorithm. Other authentication and security systems may implement the Needham-Schroeder protocol or some other symmetric encryption algorithm. Other systems may also use a Needham-Schroeder Public-Key Protocol or some other protocol.